John Sheridan was left regretting the decision not to change his line-up as Plymouth crashed to a 3-0 defeat at Rochdale.
Goals from Jamie Allen, Ian Henderson and Michael Rose handed Keith Hill's side the points and lifted the home team up to second in the League Two table.
Plymouth had to play the last 40 minutes with just 10 men after Andres Gurrieri was sent off for elbowing Jack O'Connell in the face.
But visiting manager Sheridan felt the damage was done in the first half and was expecting more from his team, who are themselves looking to break into the play-off positions.
"I thought we were very flat in the first half," he said. "I went with the same team as the last game and put my trust in the players given the performances we've had of late.
"But I think that was the wrong decision and looking at that first half I felt I should probably have put one or two fresh faces in there.
"We got off to a bad start and conceded a poor, poor goal. We were really flat and the only time we really showed up was just after half-time when we made a couple of changes.
"We were right in the game for the first few minutes of the second half and looked much better - but the sending-off didn't help. That made things really difficult for us.
"We probably had the two best chances in the game but it's a bad day at the office and we just need to pick ourselves up."